Wells are generally drilled into the ground or ocean bed to recover natural deposits of oil and gas, as well as other desirable materials that are trapped in geological formations in the Earth's crust. As wells are typically drilled using a drill bit attached to the lower end of a “drill string.” Drilling fluid, or mud, is typically pumped down through the drill string to the drill bit. The drilling fluid lubricates and cools the bit, and may additionally carry drill cuttings from the borehole back to the surface.
In various oil and gas exploration operations, it may be beneficial to have information about the subsurface formations that are penetrated by a borehole. For example, certain formation evaluation schemes include measurement and analysis of the formation pressure and permeability. These measurements may be essential to predicting the production capacity and production lifetime of the subsurface formation.
Reservoir well production and testing may involve drilling into the subsurface formation and the monitoring of various subsurface formation parameters. When drilling and monitoring, downhole tools having electric, mechanic, and/or hydraulic powered devices may be used. To energize downhole tools using hydraulic power, various systems may be used to pump fluid, such as hydraulic fluid. Such pump systems may be controlled to vary output pressures and/or flow rates to meet the needs of particular applications. Further, in some implementations, pump systems may be used to draw and pump formation fluid from subsurface formations. A downhole string (e.g., a drill string, coiled tubing, slickline, wireline, etc.) may include one or more pump systems depending on the operations to be performed using the downhole string. However, traditional pump systems may be limited in operation by the range of flow rates that may be achieved.